Abstract:

An aircraft thrust bearing assembly utilizing a U-shaped bearing disposed
over a portion of a thrust bearing shaft, both within a housing that is
mounted to the front of an engine utilized for driving an aircraft
propeller. The thrust bearing shaft rides in the U-shaped bearing,
wherein the U-shaped bearing separates the thrust bearing shaft from the
housing. The front of the thrust bearing shaft has a mounting plate for
attachment of a propeller, the mounting plate being machined to be
perpendicular to the rotational axis of the thrust bearing shaft. The
rear of the thrust bearing shaft comprises an outer surface adapted to
receive a gear press-fitted thereon and an aperture within the shaft that
is dimensioned to fixedly receive therewithin an end portion of the
crankshaft of the engine being selected for propulsion of the aircraft.

Claims:

1. A thrust bearing for an aircraft engine, said thrust bearing
comprising:a principal rotational axis;front portion having a surface
adapted for mounting a propeller thereto, wherein said surface is
perpendicular to said principal rotational axis of said thrust bearing;a
middle portion;a rear portion; anda U-shaped bearing in rotational
communication with said thrust bearing, and wherein said U-shaped bearing
is disposed on said middle portion.

2. The thrust bearing of claim 1, wherein said U-shaped bearing is a split
U-shaped bearing.

3. The thrust bearing of claim 1, wherein a gear is disposed on said rear
portion of said thrust bearing, and wherein said gear is operatively
connected to a camshaft gear.

4. The thrust bearing of claim 3, wherein said gear is machined on said
rear portion.

5. The thrust bearing of claim 3, wherein said gear is press-fit onto a
gear land formed on said rear portion.

6. The thrust bearing of claim 1, further comprising an oil seal.

7. The thrust bearing of claim 1, wherein said thrust bearing is
operatively connected to an engine crankshaft, and wherein said thrust
bearing and said engine crankshaft are aligned, and wherein said middle
portion of said thrust bearing and said engine crankshaft are machined to
final dimensions with a coincident axis once aligned.

8. The thrust bearing of claim 7, further comprising an aperture
therethrough.

9. The thrust bearing of claim 8, wherein said crankshaft is secured via
an interference fit into said aperture.

10. The thrust bearing of claim 1, wherein said thrust bearing is disposed
within a housing, and wherein said housing is secured to said aircraft
engine.

11. The thrust bearing of claim 10, wherein said U-shaped bearing is
retained within and by said housing.

12. The thrust bearing of claim 11, wherein said thrust bearing is in
rotational communication with said U-shaped bearing.

13. The thrust bearing of claim 12, wherein said thrust bearing comprises
disc walls that define said middle portion, and wherein said middle
portion is dimensioned to receive said U-shaped bearing.

14. The thrust bearing of claim 13, wherein said housing and said U-shaped
bearing restrain said disc walls of said thrust bearing from movement
along said principal rotational axis.

15. An aircraft engine comprising the thrust bearing of claim 1.

16. A method of manufacture of an aircraft thrust bearing, said method
comprising the steps of:drilling an aperture in a metal blank
core;machining a front portion, a middle portion, a rear portion, a first
disc and a second disc on said metal blank core to form a thrust
bearing;press-fitting said thrust bearing to said crankshaft of an
engine;grinding said crankshaft and said thrust bearing together to
result in a coincident rotational axis;grinding a mounting plate front
surface perpendicular to said rotational axis of said thrust bearing,
wherein said front surface is adapted to receive an aircraft propeller;
anddisposing a U-shaped bearing in rotational communication with said
middle portion.

17. The method of manufacture of claim 16, said method further comprising
the step of:machining a gear integrally on the thrust bearing.

18. The method of manufacture of claim 16, said method further comprising
the step of:machining a gear land on said thrust bearing to accommodate a
gear press-fit thereon.

19. The method of manufacture of claim 16, said method comprising the step
of:removing an existing gear bushing from an engine crankshaft.

20. A method of use of an aircraft thrust bearing, said method
comprising:installing said aircraft thrust bearing directly to a
crankshaft of an engine;installing a housing around said thrust
bearing;disposing a U-shaped bearing between said aircraft thrust bearing
and said housing; andinstalling said housing on said engine.

21. The method of claim 20, said method further comprising the steps
of:separating left and right case halves of said engine;replacing said
crankshaft of said engine with an alignment tool;securing said left and
right engine case halves together;utilizing said alignment tool to
support said housing, prior to, and during, assembly of said housing to
said engine;securing left and right housing halves together around said
alignment tool;installing said housing to said engine;once aligned,
separating said left engine case half having said left housing half
secured thereto from the right engine case half having the right housing
half secured thereto;removing said alignment tool;installing said thrust
bearing having said crankshaft secured thereto in said engine;
andsecuring said engine case halves and said housing halves together.

Description:

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0001]None

PARTIES TO A JOINT RESEARCH AGREEMENT

[0002]None

REFERENCE TO A SEQUENCE LISTING

[0003]None

BACKGROUND OF THE INVENTION

[0004]1. Technical Field of the Invention

[0005]The present invention relates generally to thrust bearings for
aircraft engines, and more specifically to a thrust bearing with housing
for installation on the crankshaft of an engine for an experimental
aircraft.

[0006]2. Description of Related Art

[0007]Many aircraft enthusiasts enjoy and even prefer to construct their
own aircraft, which are typically known as experimental aircraft. Often
such aircraft utilize standard aircraft engines, but occasionally, other
non-aircraft engines may be utilized.

[0008]Due to the need to simplify construction and cost, such enthusiast
aircraft typically utilize air-cooled engines, rather than those cooled
by glycol or other fluids. Accordingly, engines selected for use will
often be chosen from the selection of available automotive air-cooled
engines.

[0009]One such engine that has been adapted from automotive to aircraft
use is the horizontally-opposed six-cylinder engine developed in the
1950s by the Chevrolet Division of General Motors for the Corvair
automobile. This engine is particularly suited due to its lightweight
aluminum crankcase/aluminum heads construction and air-cooled cylinders,
resulting in improved airflow over the cylinder cooling fins and
providing ready access for ease of maintenance. In fact, it may well be
said that the Corvair engine is even more suited to aircraft use than for
automobiles, because for aircraft use the engine does not require a
blower to pass air over the cooling fins. Further, because of its
construction, the Corvair engine may be readily adapted to use as an
aircraft engine.

[0010]Aircraft engines require a thrust bearing to support the weight and
loads of the rotating propeller, and this thrust bearing must prevent
undue forces being exerted on the engine components to prevent untoward
wear and deterioration. Typically, the engines utilized by enthusiasts
for their experimental aircraft are direct drive; that is, the propeller
is driven at the same rotation rate as the engine crankshaft and is
connected directly to the crankshaft. Unfortunately, this direct drive
construction, coupled with aircraft maneuvers, may result in gyroscopic,
asymmetric and bending loads (as opposed to the torque loads for which
the crankshaft is particularly designed) that have a deteriorative effect
on the crankshaft, particularly causing it to crack. Accordingly,
horsepower must be restricted to avoid such deterioration.

[0011]Therefore, it is readily apparent that there is a need for an
aircraft thrust bearing assembly to overcome the aforementioned
deficiencies for use in combination with engines that may not be
traditionally utilized for aircraft.

BRIEF SUMMARY OF THE INVENTION

[0012]Briefly described, in a preferred embodiment, the present invention
overcomes the above-mentioned disadvantages and meets the recognized need
for such a device by providing an aircraft thrust bearing assembly, a
method of manufacture of same and a method of use of same, wherein the
aircraft thrust bearing utilizes a U-shaped bearing disposed over a
portion of a thrust bearing shaft, and wherein the U-shaped bearing and
thrust bearing shaft are disposed within a housing that is mounted to the
front of an engine utilized for driving an aircraft propeller, thereby
extending and supporting the engine's crankshaft and permitting higher
horsepower engines to be utilized. The thrust bearing shaft rides on the
U-shaped bearing, wherein the U-shaped bearing separates the thrust
bearing shaft from the housing. A suitable U-shaped bearing has been
found to be the crankshaft bearing from a 350 cu. in. Chevrolet engine,
although it will be recognized by those skilled in the art that other
U-shaped bearings could be utilized along with the thrust bearing shaft
of the preferred embodiment.

[0013]The front of the thrust bearing shaft has a mounting plate for
attachment of a propeller, wherein the mounting plate is machined to be
perpendicular to the rotational axis of the thrust bearing shaft. The
rear of the thrust bearing shaft comprises an outer surface adapted to
receive a gear press-fitted thereon, and an aperture within the shaft
that is dimensioned to fixedly receive therewithin an end portion of the
crankshaft of the engine being selected for propulsion of the aircraft.
The crankshaft/thrust bearing combination, along with the aforementioned
propeller mounting plate are ground by a crankshaft grinding machine once
assembled to provide a combination having a true coincident rotational
axis.

[0014]The preferred embodiment provides ease of assembly and ease of
maintenance, while readily adapting a propeller to the engine. The
housing is readily accessible for removal of the U-shaped bearing and/or
thrust bearing shaft. The preferred embodiment provides a stable
rotational thrust bearing assembly that facilitates adaptation of
existing automobile (or other) engines for use with an aircraft.

[0015]According to its major aspects and broadly stated, the present
invention in its preferred form is an aircraft thrust bearing assembly, a
method of manufacture and a method of use, the thrust bearing assembly
comprising a principal rotational axis, a front portion having a surface
adapted for mounting a propeller thereto, wherein the surface is
perpendicular to the principal rotational axis of the thrust bearing, a
middle portion, a rear portion and a U-shaped bearing in rotational
communication with the thrust bearing. The U-shaped bearing preferably
comprises a split U-shaped bearing.

[0016]The thrust bearing is operatively connected to the engine's
crankshaft. The thrust bearing has an aperture therethrough into which
the crankshaft is secured via an interference fit. A gear is disposed on
a rear portion of the thrust bearing and is operatively connected to a
camshaft gear of the engine. The gear may alternately be machined on the
rear portion of the thrust bearing or press-fit onto a gear land formed
on the rear portion.

[0017]The thrust bearing is in rotational communication with the U-shaped
bearing, which is retained within and by the housing, the housing being
secured to the front of an aircraft engine. The thrust bearing comprises
disc walls that define the middle portion thereof, and the middle portion
is dimensioned to receive the U-shaped bearing. The housing and the
U-shaped bearing restrain the disc walls of the thrust bearing from
movement along the principal rotational axis of the thrust bearing.

[0018]The thrust bearing is manufactured by drilling an aperture in a
metal blank core, machining a front portion, a middle portion, a rear
portion, a first disc and a second disc on the metal blank core, thereby
forming the thrust bearing. The thrust bearing is press-fit in
interference fit to a crankshaft of an engine. The combination is then
machined to final dimensions to ensure a true coincident rotational axis,
and a mounting plate front surface is ground perpendicular to the
rotational axis of the thrust bearing, wherein the front surface is
adapted to receive an aircraft propeller. The gear may be machined
integrally on the thrust bearing or press-fit on a gear land thereon.

[0019]The thrust bearing is installed directly on the crankshaft of the
engine and a housing is installed around the thrust bearing. Disposed
between the aircraft thrust bearing and the housing is a U-shaped
bearing. The housing with thrust bearing and U-shaped bearing therein is
installed on the aircraft engine.

[0020]To properly align during assembly, the left and right case halves of
the engine are separated, the crankshaft is replaced with an alignment
tool, the left and right engine case halves are reassembled together, and
utilizing the alignment tool to support the housing, the housing is
assembled on the engine with the left and right housing halves secured
together around the alignment tool, the housing then being installed on
the engine.

[0021]The aligned assembly is then separated into the left engine case
half and the left housing half remaining secured thereto on the one hand,
and the right engine case half and the right housing half remaining
secured thereto on the other hand. The alignment tool is then removed and
the thrust bearing with the crankshaft secured thereto is installed in
the engine, and the engine case halves and housing halves are secured
back together.

[0022]More specifically, the present invention is an aircraft engine with
a thrust bearing assembly comprising a thrust bearing shaft, a U-shaped
bearing, an oil seal, a housing and a gear. The thrust bearing shaft has
a mounting plate for a propeller that is secured to the front of the
mounting plate by fasteners.

[0023]The thrust bearing shaft is manufactured by drilling an aperture in
a metal blank core. The front portion, middle portion, rear portion,
first and second discs are formed by machining. A gear land to
accommodate a gear to operatively couple with the engine's cam gear is
machined, or, alternately, the gear may be integrally formed. The thrust
bearing shaft is then press fit to the crankshaft, the combination is
ground to final dimension to ensure a true coincident axis, and the
mounting plate is ground to produce a front surface perpendicular to the
rotational axis of the thrust bearing shaft.

[0024]The thrust bearing shaft has a front portion, a middle portion and a
rear portion. The front portion and the middle portion are separated by a
first disc wall and the middle portion and the rear portion are separated
by a second disc wall. The disc walls define the limits of travel of the
thrust bearing shaft on the U-shaped bearing, and retain the propeller,
preventing same from pulling the thrust bearing assembly out of the
engine under thrust load. The U-shaped bearing comprises, for exemplary
purposes only, a split U-shaped bearing formed from a first bearing half
and a second bearing half (such as, for exemplary purposes only, a
Chevrolet 350 cu. in. engine crankshaft U-shaped bearing) that together
form the U-shaped bearing that is disposed around the middle portion of
the thrust bearing shaft.

[0025]The rear portion of the thrust bearing shaft has a gear land
thereon, onto which a gear is press fit. The rear portion also has an
aperture therein that is dimensioned to fixedly receive an engine
crankshaft in interference fit.

[0026]The housing comprises a left housing half and a right housing half
that are assembled together and secured by fasteners around the thrust
bearing shaft, U-shaped bearing and oil seal, thereby securing the shaft,
U-shaped bearing and oil seal within the housing. The housing is
dimensioned to mate with the front of the engine, being secured to same
via fasteners.

[0027]The housing also has a front, a rear, an oil seal seat, a front
opening, a rear opening, an oil feed opening, an oil feed line, an oil
drain, a bearing opening and a bearing riding surface. The bearing riding
surface dimensionally restrains the U-shaped bearing once the housing is
in place around the thrust bearing shaft with the U-shaped bearing
installed thereon. Oil is fed via the oil feed line from an oil reservoir
to the oil feed opening to lubricate the U-shaped bearing and the thrust
bearing shaft. Excess oil drains away via the oil drain.

[0028]In use, a gear is press fit onto the thrust bearing shaft at the
gear land, and the engine crankshaft is inserted into the aperture and
secured therewithin by an interference fit. The oil seal halves are
disposed within the oil seal seat of the housing. The first and second
halves of the U-shaped bearing are disposed around the middle portion of
the thrust bearing shaft and the housing halves are secured together and
to the engine. A propeller is then secured to the mounting plate of the
thrust bearing shaft via fasteners. The gear engages a cam gear that is
disposed on the engine's camshaft. Thus rotation of the crankshaft and
camshaft are operationally coupled.

[0029]To ensure proper alignment of the aircraft thrust bearing assembly,
an alignment tool replaces the crankshaft and is utilized to support the
housing, prior to, and during, assembly of the housing to the engine.
Accordingly, the alignment tool is installed in the engine, replacing the
engine's crankshaft and the left and right engine case halves are secured
together. The left and right housing halves are secured together around
the alignment tool and the housing is subsequently installed to the
engine. Once the housing is aligned, the engine case half with the left
housing half secured thereto is separated from the engine case half with
the right housing half secured thereto, and the alignment tool is
removed. Finally, the crankshaft with the thrust bearing assembly press
fit thereon is installed in the engine, and the engine case halves and
housing halves are secured together.

[0030]Accordingly, a feature and advantage of the present invention is its
ability to adapt a propeller to an existing engine while providing
support to the propeller and while reducing deteriorative forces on the
engine.

[0031]Another feature and advantage of the present invention is its
ability to be readily removed and replaced within its housing.

[0032]Still another feature and advantage of the present invention is its
ability to utilize existing standard wearable components.

[0033]Yet another feature and advantage of the present invention is that
it provides for lubrication of the thrust bearing and U-shaped bearing.

[0034]Yet still another feature and advantage of the present invention is
that it provides for accurate alignment of the thrust bearing, crankshaft
and propeller combination.

[0035]These and other features and advantages of the present invention
will become more apparent to one skilled in the art from the following
description and claims when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0036]The present invention will be better understood by reading the
Detailed Description of the Preferred Embodiment with reference to the
accompanying drawing figures, in which like reference numerals denote
similar structure and refer to like elements throughout, and in which:

[0037]FIG. 1 depicts a cutaway perspective view of an engine with a thrust
bearing and housing according to a preferred embodiment;

[0038]FIG. 2 is a front view of a housing component according to a
preferred embodiment;

[0039]FIG. 3 is a side view of a left housing component according to a
preferred embodiment;

[0040]FIG. 4 is a side view with partial cross-sectional view of a thrust
bearing with housing according to a preferred embodiment shown installed
on an engine crankshaft;

[0041]FIG. 5 depicts a side view of a thrust bearing component according
to a preferred embodiment; and

[0042]FIG. 6 is an exploded perspective view of a housing with split
U-shaped bearing and oil seal according to a preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

[0043]In describing the preferred embodiment of the present invention, as
illustrated in FIGS. 1-6, specific terminology is employed for the sake
of clarity. The invention, however, is not intended to be limited to the
specific terminology so selected, and it is to be understood that each
specific element includes all technical equivalents that operate in a
similar manner to accomplish similar functions.

[0045]Thrust bearing shaft 100 further comprises front portion 150, middle
portion 170 and rear portion 190, wherein front portion 150 and middle
portion 170 are separated by first disc wall 160, and wherein middle
portion 170 and rear portion 190 are separated by second disc wall 180.
First disc wall 160 and second disc wall 180 define the limits of travel
of, and retain, thrust bearing shaft 100 within housing 30 on U-shaped
bearing 230, thereby preventing propeller P from being pulled out of the
engine due to its thrust loads. U-shaped bearing 230 comprises, for
exemplary purposes only, a split U-shaped bearing having first bearing
half 230A and second bearing half 230B, wherein bearing halves 230A, 230B
together form U-shaped bearing 230 when bearing halves 230A, 230B are
disposed around middle portion 170 of thrust bearing shaft 100. U-shaped
bearing 230 is supported and fixedly maintained by its contact with
housing 30. It has been found that a Chevrolet 350 cu. in. engine
crankshaft U-shaped bearing is well suited as U-shaped bearing 230, but
any suitable U-shaped bearing could be utilized without departing from
the spirit of the preferred embodiment.

[0047]Thrust bearing shaft 100 is manufactured by drilling aperture 175 in
a metal blank core. Front portion 150, middle portion 170 and rear
portion 190 are formed by machining to near final dimensions, such as,
for exemplary purposes only, on a CNC lathe, and first disc 160, second
disc 180, and gear land 195 are also similarly formed by machining. Gear
120 may alternately be integrally formed. Thrust bearing shaft 100 is
press fit to crankshaft 110 after first removing the original gear with
bushing that would ordinarily engage the camshaft gear 130, crankshaft
110 with thrust bearing shaft 100 secured thereon is ground on a
crankshaft grinding machine as more fully detailed hereinbelow, and
finally, mounting plate 115 is ground to produce front surface 105 that
is perpendicular to rotational axis 380 of thrust bearing shaft 100.

[0050]In use, gear 120 is press fit onto thrust bearing shaft 100 at gear
land 195, existing gear bushing 113 is removed from existing crankshaft
110, and crankshaft 110 is subsequently inserted into aperture 175 via
entrance 185, wherein crankshaft 110 is secured within aperture 175 by an
interference fit. It will be recognized by those skilled in the art that
other means for securing crankshaft 110 within thrust bearing shaft 100
could be utilized without departing from the spirit of the preferred
embodiment.

[0051]Crankshaft 110 with thrust bearing shaft 100 secured thereon is
subsequently turned in a crankshaft grinding machine, wherein crankshaft
lobes 112 and middle portion 170 of thrust bearing shaft 100 are turned
to final dimensions while in true and final alignment to form a
coincident rotational axis 380.

[0055]Although particularly suited to retrofit existing engines, thrust
bearing assembly 20 could be incorporated as part of an
originally-manufactured engine. Further, thrust bearing shaft 100 and
crankshaft 110 could be formed as a unit from a single core.

[0056]The foregoing description and drawings comprise illustrative
embodiments of the present invention. Having thus described exemplary
embodiments of the present invention, it should be noted by those skilled
in the art that the within disclosures are exemplary only, and that
various other alternatives, adaptations, and modifications may be made
within the scope of the present invention. Merely listing or numbering
the steps of a method in a certain order does not constitute any
limitation on the order of the steps of that method. Many modifications
and other embodiments of the invention will come to mind to one skilled
in the art to which this invention pertains having the benefit of the
teachings presented in the foregoing descriptions and the associated
drawings. Although specific terms may be employed herein, they are used
in a generic and descriptive sense only and not for purposes of
limitation. Accordingly, the present invention is not limited to the
specific embodiments illustrated herein, but is limited only by the
following claims.